In vitro culturing of cells provides materials necessary for research in pharmacology, physiology, and toxicology. An exemplary vessel inclusive of a suitable environment for culturing cells is a common laboratory flask. The cells typically attach to and grow on the bottom surface(s) of the flask, immersed in a suitable sustaining media. The flask is then stored in an incubator to maintain the proper temperature and atmosphere for specified growth conditions. Advancements in improving cellular growth conditions, however, have revitalized the standard flask market. With the advent of cell-based high throughput applications, cell culture vessels have been developed to provide an increased surface area for cell growth while also providing necessary gas exchange. These systems employ traditional cell culture vessels including common flasks, roller bottles, cell culture dishes, and multi-layered cell growth devices. In addition, automation permits manipulation of the cell culture vessel or apparatus much like that performed by the manual operator. Current flasks, however, do not allow for complete drainage of fluid from the vessel. Therefore, when removing nutrient media and/or cellular contents from the flask, undesirable fluid (such as cell excretions/waste products, dead-cells contaminants, or other toxins) remains in the vessel. Even if by-products of cellular waste do not pose a significant problem, it is typically necessary to remove and wash all media from the vessel to prevent any inhibitory function of subsequent chemical additives such as trypsin (utilized when harvesting cells from the flask).
Although fluid may be aspirated from the vessel, or the vessel constructed with a sloping feature along the opposite end wall to enable easier removal of media with a canula or pipette tip when-the flask is arranged in position with the neck facing upward, any remaining fluid may still pool at the bottom-most portion of the sloped end wall. This assumes that a canula or tip is capable of extending vertically down from the neck and engaging the opposing end wall. On the other hand, it may be even more so desirable to pour fluid out of the vessel. When pouring liquid contents from a vessel, however, capillary action can cause some of the fluid to be retained in comers or where vessel walls meet perpendicular to each other, including near the drain port where the fluid becomes trapped in the corners of a manifold below the pouring outlet. This can lead to greater fluid retention in the vessel when the fluid clings in these locations rather than moving toward the port. In particular, when pouring liquid volumes from a port, the adherent and coherent properties of the liquid cause different volumes of fluid to be retained in the vessel. Furthermore, fluid that remains in the vessel, such as dead cells, cellular debris or the by-products thereby produced, may contaminate any other growth surface or the replacement media. One solution is to bang the vessel to try to use the fluids momentum to break the capillary force. This can obviously dent or damage the external structure of the flask, however, and possibly disrupt internal structural components of the flask as well, including destruction of internal growth surface areas, or impairment of individual flaskettes internal to the unitary vessel. A canula or syringe tip to collect the remaining media is also not capable of reaching the corner areas of the vessel, especially not flexible or durable enough to withdraw any fluid retained in the hard to reach front corners and edges of the vessel nearest the port.
There is a need for a cell culture vessel that is designed for reducing problems associated with removing fluid from the vessel. The cell culture vessel will assist in draining fluid from the internal surfaces of the vessel, and do so as thoroughly as possible. In addition, the cell culture vessel will reduce fluid retention in the corners of the vessel or near the drain port, further minimizing any contaminating remnants in the vessel during removal of nutrient media or cellular contents. Thus, the fluid will be directed away from internal growth surfaces and toward an outlet or drain port. The cell culture vessel will permit lower fluid retention in its total internal volume and be capable of conforming to current flask designs. The desired cell culture vessel will also be suitable for use in the performance of high throughput assay applications that commonly employ robotic manipulation. Additional advantages will be apparent in the following illustrations and detailed description.